.diagram {
  max-width: 700px;
  margin: 2rem auto;
  padding: 1rem;
  text-align: center;
}

.flow {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.box {
  background: #f0f0f0;
  border: 1px solid #ccc;
  padding: 1rem 1.5rem;
  border-radius: 8px;
  width: 100%;
  max-width: 450px;
  box-shadow: 0 1px 4px rgba(0,0,0,0.1);
}

.box small {
  display: block;
  font-size: 0.9rem;
  color: #555;
  margin-top: 0.25rem;
}

.arrow {
  font-size: 1.5rem;
  color: #888;
}